This invention relates to a drill for use in a boring machine and having a tool holder with two cutter bars, each having a cutter projecting radially from the periphery of the tool holder, the cutter bars being movably mounted in a radial direction in a recess passing through the tool holder, the cutter bars being fixable in their respective positions. Thus such drills serve for boring of drilled holes, the radial spacing between the cutters and the longitudinal axis of the tool holder being alterable, in order to adapt the drill to holes of various diameters, or in order to vary the thickness of chip material removed during processing. Because during processing of drilled holes considerable forces have to be applied by the cutters, correspondingly large torques must be transmitted by the drill and if the range of usefulness of the drill in relation to the forces to be applied during cutting is not to be limited, the construction of the drill should be extremely robust.